This article discusses a survey to investigate the problem of the health literacy of leisure runners. The survey was conducted in 2016 in Poland among 963 participants of the DOZ Marathon Lodz with PZU [Polish Insurance Company] . A specially developed scale for measuring the participants’ level of health literacy (−3, 23 points) was used, and the survey answers were evaluated by medical doctors. As the average score was 3.16, the surveyed population was shown to lack information about the medical and health consequences of running. The people who were relatively better informed were women and younger runners (and additionally single runners and those not active on the labor market). An unexpected finding was that social-class affiliation, educational level, and advancement in running ability had a low degree of influence on the health knowledge of the surveyed runners. The conclusion is that a health-related motivation to train in the sport of running (which was declared to be a key factor in many studies) is grounded in common knowledge, while the majority of leisure runners are unacquainted with the actual risks and benefits of running